A bearing usually provides an inner ring and an outer ring, the rings being in rotation relative to one another. The rings may together form a bearing chamber in which rolling elements, such as balls, needles or rollers are housed.
A bearing is designed to be mounted in a housing of a mechanical system, notably between a static mechanical element and a mechanical element moveable in rotation such as to support the relative rotation of same.
Bearings are fitted with sealing means to ensure that the bearing is sealed, i.e. to prevent the ingress of external elements such as particulate matter, contaminants or water into the bearing chamber. These sealing means may provide seals rigidly connected to one of the rings, preferably rotary rings, and in sliding contact with the other ring.
However, friction between the seal and a ring during rotation of the bearing results in a friction torque opposing the movement. This results in low efficiency, an increase in temperature and degradation of the seal, the performance of which is reduced as it is used.
A bearing may also be fitted with seals or flanges mounted on one of the rings and providing a small passage to the other ring. Such sealing means, referred to as labyrinth seals, are not in contact with the other ring and avoid the drawbacks related to contact seals.
However, although small, labyrinth seals cannot guarantee an absolute seal of the bearing since the ingress of external elements is still possible. Furthermore, the lubricant present in the bearing chamber can escape through the labyrinth seal, in particular during transportation of the bearing from the manufacturing site to a constructor of the related final application.
The invention is in particular intended to address these problems by proposing a sealed bearing assembly having reduced friction torque when in use that is simple to make and to assemble, and that is modular in terms of use and adaptation to numerous applications.
For this purpose, the invention relates to a bearing assembly comprising a bearing provided with a first ring with a hole, two front edges and an outer cylindrical surface, and a second ring with a hole, two radial edges and an outer cylindrical surface. The first and second rings may be in relative rotation about a central axis. The bearing also includes at least one row of rolling elements housed in a bearing chamber formed between an outer cylindrical surface and a hole of the rings. The first and second rings and the rolling elements determine a pitch diameter of the bearing.
According to the invention, the assembly also includes at least one sealing means provided with an engagement portion rigidly connected to one of the rings that can be rotary and a tapered annular body extending from the engagement portion towards the other ring, such that when idle the body forms a non-zero angle with a plane perpendicular to the pitch diameter and is in direct or indirect contact with the other ring of the bearing.
The rings of the bearing and the rolling elements determine that the pitch diameter of the bearing is an axis of rotation of the rolling elements, the rings being in relative rotation parallel to this axis located between the rings.
Consequently, a sealing means is rigidly connected to a ring of the bearing, but with a tapered annular body. The operating mode of a sealing means according to the invention is as follows. When idle, i.e. when there is no relative rotational movement of the rings of the bearing, the body of the sealing means is oblique in relation to the perpendicular of the pitch diameter, extending from the ring to which same is attached with an angular gap in relation to the perpendicular of the ring. When the ring bearing the sealing means is in rotation about the central axis, a centrifugal force is applied to the body of the sealing means, in particular to the free end of same. When the rotational speed of the ring is sufficient, the body is inclined in relation to the initial position of same towards the plane perpendicular to the pitch diameter that passes through a joining zone between the engagement portion and the tapered annular body. A midpoint of the joining zone forms a pivot of rotation. The body, initially in direct or indirect contact with the other ring of the bearing, is then shifted in relation to the ring. Consequently, in the operating mode of the bearing, i.e. when the ring fitted with at least one sealing means is in rotation, the sealing means is no longer in contact with the other ring.